Preliminary injunction
Definition
A preliminary injunction is a court order that pauses a challenged action, like enforcement of a law or policy, while a lawsuit over it is still being litigated. It is temporary relief, not a final ruling on the merits, but it can freeze a policy in place for months or years while the case proceeds.
Why it matters
A preliminary injunction can neutralize a law or executive action almost immediately after it is signed, long before any court reaches a final decision on whether it is actually legal, making the request for one of the highest-leverage moves in litigation against new government action.
Seen in the wild
Federal courts apply the four-factor test from the Supreme Court's 2008 decision in Winter v. Natural Resources Defense Council: likelihood of success on the merits, likelihood of irreparable harm, the balance of equities, and the public interest.1